6 Jointer
6.1 Jointer Overview
The jointer is one of the first steps in machining rough lumber. Solid wood that first arrives in the woodworking shop is rarely used as is. Together with the planer and table saw, the jointer is used to machine or surface straight, square stock so that tight-fitting and accurate joinery can be cut. The process of creating straight and true lumber is often referred to as machining, milling, or surfacing.
The jointer makes small, successive cuts in relation to its large, flat cast iron bed. It creates a flat and smooth surface by removing the high spots from a board. Its most common use is to flatten the face of a board and straighten an edge, 90° to the flat face. With these two square and true references, the board can then be processed on the planer and table saw to completely remove bows, twists, and cups from a board.
In practice, the jointer is not used for a wide range of operations. It is used almost primarily as described above. However, more advanced operations on the jointer can include sizing parts (i.e. cabinet doors), cutting tapers and bevels, and rabbets.
A revolving cutterhead is located between the infeed and outfeed tables. The depth of cut is adjusted by lowering and raising the infeed table in relation to the cutterhead. For standard operation, the outfeed table is set to the same height as the cutterhead. The back fence is typically set at 90° to the table. The fence can be tilted and also slides closer or farther from the jointer’s back edge. A jointer guard must be used at all times. It is spring-operated; the board pushes it out of the way during the cut, and it closes quickly after the board passes over the cutterhead.
6.2 Jointer Operation
Stock is normally face-jointed first, then edge-jointed second, with the newly jointed face pressed tight against the fence. With a properly set fence and correct operation, the jointed face and edge will be 90° to each other. The stock is then ready to be sent through the planer.
Although the process is simple, controlling the board over the cutterhead involves some subtleties. The operator is wholly responsible for keeping the board moving at an appropriate and consistent speed, as well as keeping the board referenced tight against the fence. It is very important to work safely at the jointer and to completely understand the process so that the resulting board is true and straight.
To joint stock, place it on the infeed table and pass it from right to left over the cutterhead. The grain of the wood should slope down and to the right whenever possible in order to avoid grain tear-out. Concentrate downward pressure on the stock over the infeed table at the beginning of a cut, shifting pressure to the stock on the outfeed table as the cut progresses.
It’s extremely important to understand the jointer references. When face-jointing, the important reference is the outfeed table. As soon as there is enough material past the cutter head, concentrate pressure and attention on the outfeed side. Thinking about pulling through the jointer rather than pushing also keeps your hands safely past the cutterhead rather than over or in front of.
When edge-jointing, you must also be concerned with keeping the board tight against the fence. Attention and concentration should still be on the outfeed side once enough of the board passes over the cutterhead.
Feed speed is very important. A slower, consistent feed rate is safer and yields a much higher quality cut with fewer machining marks.
As a beginner, turn the jointer off after each pass and check your material. Look closely at the surface, you can often see the result of a pass that was too fast as small waves and dips. As you gain skill and practice at the jointer, you will develop a workflow and will not have to check after each pass. Learn to listen to the machine, you can hear when a complete pass over the surface is cut, or if you move too fast and bog down the motor.
Use chalk or a lumber crayon to mark surfaces before jointing. As the crayon disappears, you know that the surface has been freshly cut.
Improper jointer machine setup can create wedged or tapered boards or snipe at the end of a board. Snipe is caused when the board drops onto the cutterhead, resulting in a dip on the surface of the board. Jointers require precise setup during preventative maintenance schedules and blade changes. If you think the jointer is not performing as it should, speak to the shop supervisor or technician.
Face jointing
Check the board for cups and twists on a flat reference surface. As you do this, check for any foreign objects like nails, staples, loose knots, and gravel. If the face was previously surfaced and there is no cup or twist, the board can be edge jointed or go straight to the planer. Cups should be corrected with the concave side down, providing the most stability.
Twists are the hardest to correct at the jointer. Locate the corners that contact the table and focus pressure on these points until the board does not rock as it passes over the cutterhead. Double check your rough measurements, cutting a board down in length before jointing often makes it easier to correct twists.
- Place the board face down on the outfeed side, making sure the guard covers the cutterhead.
- Adjust the width of cut if necessary by moving the fence forward or backward.
- Check and adjust the depth of cut, 1/16” is a standard cut. Cutting less will create a smoother surface for a finish pass.
- Double-check that the board is not in contact with the cutterhead and turn the jointer on.
- Using a push stick in either hand, push the board slowly and steadily over the cutterhead, maintaining control the entire cut.
- Let the guard swing shut and turn off the jointer.
- Wait for the cutterhead to stop spinning and check to see if the board face is flat. Joint again if necessary.
Edge jointing
Check for bows along the edge. Joint with the bow down and/or the edge with fewer defects. Edge grain runout is very common and can cause bad tear-out at the jointer. It’s not always possible to joint bow down and avoid tear-out. If this is the cause, it is better to rip a straight edge on the bandsaw or with a jigsaw, and then edge joint.
- Check the fence for ninety degrees. Adjust if necessary.
- Pass the board over the jointer using push sticks with the jointed face against the fence and the edge to be cut down on the table.
- Mark both jointed face and edge with a pencil or crayon so you can use these as references during further steps.
ALWAYS make sure the guard is in place before starting the machine.
ALWAYS make sure the wood is not touching knives before starting.
ALWAYS check the fence for square before edge jointing with the cutterhead stopped. NEVER move the guard to check for square.
DO joint cupped boards with the cup down.
DO joint bowed boards with the bow down.
ALWAYS use a push pad or push stick in both hands. NEVER use the jointer without a push pad or push stick.
ALWAYS make adjustments with the machine completely stopped.
ALWAYS stand to the side to avoid kickback, NEVER behind the board being jointed.
ALWAYS use a bench brush to clean shavings from the table. NEVER use your hand.
NEVER apply pressure to the board with your hand above the cutterhead.
DO NOT joint painted, varnished, or otherwise used stock. Clean stock with a wire brush before milling, this will remove any gravel or dirt that may be pressed into the board.
DO NOT joint stock shorter than 12″.
DO NOT joint stock thinner than ½”.
DO NOT edge joint stock thinner than ½”.
NEVER pull stock back out of the machine.
DO NOT joint more than 1/16″ at a pass.
NEVER joint end grain.
DO NOT joint particle board, masonite, or plywood, solid wood is the only material used on the jointer.
DO NOT let anyone distract you while you are using the jointer, ALWAYS maintain control and concentration through the entire cut.
DO NOT let your fingers come near the knives, EVER.
